Fibrous materials such as straw from flax, sisal, hemp, jute and coir, banana, among others, are used or combined with various polymers in the formation of biocomposite or bio-fiber composite materials. Biocomposite materials utilizing these fibrous materials or fibers mixed with selected polymers provide enhanced desirable properties compared with polymer-only materials. For example, biocomposite materials have the advantageous qualities of light weight, enhanced strength, corrosion resistance, design flexibility, inexpensive production, and environmental friendliness, among others over materials only formed from polymers.
However, regardless of these many beneficial properties, biocomposites normally have a low electrical conductivity as a result of the lack of or limited amount of conductivity of the fibrous materials and polymers used to form the biocomposite material. This lack of conductivity can create certain problems with regard to the end products and/or uses for the biocomposite materials, such as static charge buildups as well as limiting the applications in which the biocomposite materials can be used.
Certain prior art attempts have been made to overcome these issues and enhance the conductivity of these fibrous materials, thereby increasing the utility of the fibrous materials. Examples of these attempts center on the inclusion of conductive particles on the exterior of the fibrous materials, or on the inclusion of the particles in the structure of the polymer, thereby forming a conductive polymer for subsequent use.
Some examples of the incorporation of these conductive materials as exterior coatings are disclosed in U.S. Pat. No. 4,247,596; US2014/0138305; and US2104/0093731, each of which are expressly incorporated by reference herein in their entirety. In each of these references, a coating is applied to the exterior of a fiber in which the coating includes conductive particles therein.
In these examples, while the fibrous materials including these coatings have increased conductivity due to the presence of the conductive particles in the exterior coating, the location of the conductive particles on the exterior of the fibrous materials can be degraded over time, lessening the effectiveness of the conductivity of the coatings.
Further, in WO2014/155786, a vibration dampening composition is disclosed that includes conductive carbon black particles to assist in the conductivity of a composition having dielectric materials and piezoelectric cellulose fibers in a polymeric material. However, in this disclosure the fibers are directly formed as conductive members, a modification that can detract from the structural and other enhancements to the material in the manner of the fibrous material utilized in biocomposite formulations.
As a result, it is desirable to develop a method for adding or introducing a conductive material into a biocomposite formed with a fibrous material and polymer base that significantly enhances the electrical conductivity of the resulting biocomposite material without detrimentally affecting the other enhanced properties of the biocomposite material when compared with polymer-only materials.